1. Field of the Invention
The described embodiments relate generally to batteries for portable computing devices. More particularly, the present embodiments relate to battery packaging designs for portable computing devices.
2. Description of the Related Art
A design of a portable computing device can involve complex tradeoffs. A few factors that can be considered in the design process are cosmetic appeal, weight, manufacturability, durability, thermal compatibility and power consumption. A component that is selected on the basis of its positive contribution to one of these design factors can have an adverse impact on one of more other design factors.
A portable power source, typically, a battery of some type is an important component in the design of a portable computing device. The portable power source provides operating power for the portable computing device when it is not near a fixed power source, such as a wall outlet. Factors in selecting a portable power source can be energy density, form factor and durability.
Energy density can refer to the amount of energy per given volume or per given mass that the portable power source is capable of delivering to the portable computing device. The form factor can refer to the shape of the package containing the portable power source. For instance, portable computing devices that are slim require an overall form factor for the portable power source that is also slim. The durability can relate to containment of any damaging elements associated with a battery cell. For example, portable power sources often include liquid or gel type electrolytes that need to be contained to prevent damage to other electronic components where the packaging needs to be durable enough to contain these damaging elements under normal operational conditions.
The energy density for a portable power device, such as a battery, can be affected by the type battery cell that is employed and its associated packaging. The packaging design can affect the energy density in a number of ways. First, the energy density per mass will decrease as the mass of the packaging increases. The packaging decreases the energy density per mass because it adds mass to the system without providing additional energy. The mass of the packaging design can be constrained by durability considerations.
Second, the energy density per volume is affected by packing efficiency where the packing efficiency can be constrained by a desired form factor for the packaging design. An inefficiently packaged battery cell can have a lower energy density per volume than an efficiently packaged battery cell. As the energy density per volume decreases, the volume taken up by the portable power device increases, which can be undesirable for utilization with a portable computing device.
In a portable computing device, it is generally desirable to minimize the weight and volume of each component while still maintaining desired functionality and performance levels. Therefore, it would be beneficial to provide a housing assembly for a battery useable in at least a portable computing device that is durable, lightweight and efficiently packaged. It would also be beneficial to provide methods for assembling the battery that meet the above conditions and perform satisfactorily during operational cycling of the device.